Sulfur isotope fractionations in the Pb-S, Cu-S and Ag-S systems

抄録

As a result of the lack of data on other than the most common sulfides (pyrite, pyrrhotite, chalcopyrite, sphalerite, galena), the applicability of the sulfur isotope thermometer is restricted. The isotope fractionation among different metal-sulfides and sulfur has therefore been experimentally investigated in this study. The experiments have been carried out in dry systems by reacting pure metals with an excess of sulfur in evacuated silica glass tubes at temperatures from 280 to 700°C with reaction times from 0.3 to 3, 000 hours. The following fractionation factors have been determined for the sulfides synthesized in the three systems: 1000 lnα_PbS-S = -4.6 (10⁵T^-2) 1000 lnα_Ag2S-S = -4.6 (10⁵T^-2) 1000 lnα_CuS-S = 2.0 (10⁵T^-3) 1000 lnα_Cu9S5-S = 1.0 (10⁵T^-2)